Neurophysiological Principles 1

Question 1

What are extrafusal muscle fiber?

Answer 1

skeletal muscle fiber- contains all contractile elements.

Question 2

What are intrafusal muscle fibers

Answer 2

Sits inside extrafusal fibers. The muscle spindle and all of its components parts-sit parallel to the extrafusal fibers. (Static nuclear bag, dynamic nuclear bag, nuclear chain).

Question 3

What are the Golgi Tendon Organs (GTO)?

Answer 3

Sit between muscle and tendon. located in the musculotendinous junction and are situated in series with the extrafusal fibers

Question 4

What do the extrafusal muscle fibers contain?

Answer 4

motor neurons-Alpha motor neuron

Question 5

what do the intrafusal muscle fibers contain?

Answer 5

motor neurons-gamma motor neuron-can control motion based on info. to the brain.
sensory neurons-Ia and II-provides info to the brain.

Question 6

what do GTOs contain?

Answer 6

Sensory Neurons-Ib

Question 7

What do the intrafusal muscle fibers and GTO provide together?

Answer 7

static muscle length- what is the length of the muscle
rate of length of change-this is how fast we move
force the muscle can generate

Question 8

What does the fusimotor system and Gamma loop do?

Answer 8

participates in stretch reflexes (muscle spindle only) sends proprioceptive info to the CNS regarding movement and position of body segments
helps to regulate muscle contraction under the influence of descending motor pathways as well as afferent feedback
Is fine motor control

Question 9

Where are muscle spindles found in greatest abundance?

Answer 9

In muscles capable of intricate contractile activity
hands
eyes
neck

Question 10

What is typically in a muscle spindle?

Answer 10

one dynamic nuclear bag fiber
one static nuclear bag fiber
five nuclear chain fibers

Question 11

What are the different categories of the sensory nerve fibers?

Answer 11

Groups Ia-primary sensory (annulospiral)

Group II- secondary sensory (flowerspray)

Question 12

Where does Groups Ia of the sensory nerve fibers come from?

Answer 12

All three components of the muscle spindle.

Question 13

Where does group II of the sensory nerve fibers come from?

Answer 13

only from the static nuclear bag and nuclear chain of the muscle spindle.
from the Golgi tendon organ

Question 14

What happens to the intrafusal muscle fibers when they are stretched?

Answer 14

primary and secondary afferents fire

Question 15

What are secondary afferents of the intrafusal muscle fibers more sensitive to?

Answer 15

steady-state stretch and reports the length of muscle to the CNS

Question 16

When do primary afferents in intrafusal muscle fibers discharge more?

Answer 16

during length changing stretch and report length of muscle as well as rate of change to the CNS.

Question 17

What are three important things to know about the gamma motor neurons or fusimotor fibers?

Answer 17

nerve fivers that form the efferent or motor supply to the muscle spindle
dynamic gamma motor neurons innervate the dynamic nuclear bag
static gamma motor neurons innervate the static nuclear bag and the nuclear chain

Question 18

Which part of the gamma motor neurons is the contractile element?

Answer 18

the ends

Question 19

which part of the gamma motor unit is the sensory?

Answer 19

the middle

Question 20

Where does the gamma motor neuron innervate?

Answer 20

the contractile regions of the nuclear bag and chain

Question 21

What does the gamma motor neuron do?

Answer 21

contracts and shortens the intrafusal fibers at its ends thereby stretching the central nuclear region.
the input regulates the sensitivity of the spindle

Question 22

Where is the Golgi tendon organ located?

Answer 22

between the muscle and the tendon-sits parallel

Question 23

Where does the Golgi tendon organ sit in series with?

Answer 23

15-20 extrafusal fibers

Question 24

what is the Golgi tendon inervated by?

Answer 24

Ib afferent nerve fiver (only sensory, not motor)

Question 25

What is the Golgi tendon organ sensitive to?

Answer 25

changes in tension in the muscle and particularly sensitive to active muscle contractions and therefore monitors muscle contraction.

Question 26

When does the Golgi tendon organ fire?

Answer 26

fires steadily during passive lengthening

Question 27

What does the Golgi tendon monitor?

Answer 27

monitors muscle contraction
rate of tension change in an isotonic activation
signals the amount of tension in an isometric activation.

Question 28

What causes autogenic inhibition of the Golgi tendon organ?

Answer 28

high levels of excitation of the Ib nerve fiver

Question 29

What is autogenic inhibition?

Answer 29

self generated inhibitory process

Question 30

What does the Golgi tendon organ protect?

Answer 30

the integrity of the musculotendinous complex

Question 31

When is gamma bias produced?

Answer 31

as this system keep the spindle fibers taut or biased and thereby responsive to changes in muscle length

Question 32

When is the value of the spindle lost?

Answer 32

if contraction of the muscle unloads the muscle spindle and movement begins.

Question 33

When does active contraction of the intrafusal muscle fibers occur?

Answer 33

when the gamma system is fired

Question 34

What does the gamma bias secure?

Answer 34

Integration of agonists, synergists and antagonists as well as provides information about each muscle throughout the entire movement.